ABSTRACT
Transcranial magnetic stimulation (TMS) is a popular modulatory technique for the noninvasive diagnosis and therapy of neurological and psychiatric diseases. Unfortunately, current modulation strategies are only modestly effective. The literature provides strong evidence that the modulatory effects of TMS vary depending on device components and stimulation protocols. These differential effects are important when designing precise modulatory strategies for clinical or research applications. Developments in TMS have been accompanied by advances in combining TMS with neuroimaging techniques, including electroencephalography, functional near-infrared spectroscopy, functional magnetic resonance imaging, and positron emission tomography. Such studies appear particularly promising as they may not only allow us to probe affected brain areas during TMS but also seem to predict underlying research directions that may enable us to precisely target and remodel impaired cortices or circuits. However, few precise modulation strategies are available, and the long-term safety and efficacy of these strategies need to be confirmed. Here, we review the literature on possible technologies for precise modulation to highlight progress along with limitations with the goal of suggesting future directions for this field.
ABSTRACT
Transcranial magnetic stimulation (TMS) is a popular modulatory technique for the noninvasive diagnosis and therapy of neurological and psychiatric diseases. Unfortunately, current modulation strategies are only modestly effective. The literature provides strong evidence that the modulatory effects of TMS vary depending on device components and stimulation protocols. These differential effects are important when designing precise modulatory strategies for clinical or research applications. Developments in TMS have been accompanied by advances in combining TMS with neuroimaging techniques, including electroencephalography, functional near-infrared spectroscopy, functional magnetic resonance imaging, and positron emission tomography. Such studies appear particularly promising as they may not only allow us to probe affected brain areas during TMS but also seem to predict underlying research directions that may enable us to precisely target and remodel impaired cortices or circuits. However, few precise modulation strategies are available, and the long-term safety and efficacy of these strategies need to be confirmed. Here, we review the literature on possible technologies for precise modulation to highlight progress along with limitations with the goal of suggesting future directions for this field.
Subject(s)
Brain/diagnostic imaging , Electroencephalography , Magnetic Resonance Imaging , Neuroimaging , Transcranial Magnetic StimulationABSTRACT
Cross-modal selective attention enhances the processing of sensory inputs that are most relevant to the task at hand. Such differential processing could be mediated by a swift network reconfiguration on the macroscopic level, but this remains a poorly understood process. To tackle this issue, we used a behavioral paradigm to introduce a shift of selective attention between the visual and auditory domains, and recorded scalp electroencephalographic signals from eight healthy participants. The changes in effective connectivity caused by the cross-modal attentional shift were delineated by analyzing spectral Granger Causality (GC), a metric of frequency-specific effective connectivity. Using data-driven methods of pattern-classification and feature-analysis, we found that a change in the α band (12 Hz-15 Hz) of GC is a stable feature across different individuals that can be used to decode the attentional shift. Specifically, auditory attention induces more pronounced information flow in the α band, especially from the parietal-occipital areas to the temporal-parietal areas, compared to the case of visual attention, reflecting a reconfiguration of interaction in the macroscopic brain network accompanying different processing. Our results support the role of α oscillation in organizing the information flow across spatially-separated brain areas and, thereby, mediating cross-modal selective attention.
ABSTRACT
Cross-modal selective attention enhances the processing of sensory inputs that are most relevant to the task at hand. Such differential processing could be mediated by a swift network reconfiguration on the macroscopic level, but this remains a poorly understood process. To tackle this issue, we used a behavioral paradigm to introduce a shift of selective attention between the visual and auditory domains, and recorded scalp electroencephalographic signals from eight healthy participants. The changes in effective connectivity caused by the cross-modal attentional shift were delineated by analyzing spectral Granger Causality (GC), a metric of frequency-specific effective connectivity. Using data-driven methods of pattern-classification and feature-analysis, we found that a change in the α band (12 Hz-15 Hz) of GC is a stable feature across different individuals that can be used to decode the attentional shift. Specifically, auditory attention induces more pronounced information flow in the α band, especially from the parietal-occipital areas to the temporal-parietal areas, compared to the case of visual attention, reflecting a reconfiguration of interaction in the macroscopic brain network accompanying different processing. Our results support the role of α oscillation in organizing the information flow across spatially-separated brain areas and, thereby, mediating cross-modal selective attention.
ABSTRACT
An important and unresolved question is how human brain regions process information and interact with each other in intertemporal choice related to gains and losses. Using psychophysiological interaction and dynamic causal modeling analyses, we investigated the functional interactions between regions involved in the decision-making process while participants performed temporal discounting tasks in both the gains and losses domains. We found two distinct intrinsic valuation systems underlying temporal discounting in the gains and losses domains: gains were specifically evaluated in the medial regions, including the medial prefrontal and orbitofrontal cortices, and losses were evaluated in the lateral dorsolateral prefrontal cortex. In addition, immediate reward or punishment was found to modulate the functional interactions between the dorsolateral prefrontal cortex and distinct regions in both the gains and losses domains: in the gains domain, the mesolimbic regions; in the losses domain, the medial prefrontal cortex, anterior cingulate cortex, and insula. These findings suggest that intertemporal choice of gains and losses might involve distinct valuation systems, and more importantly, separate neural interactions may implement the intertemporal choices of gains and losses. These findings may provide a new biological perspective for understanding the neural mechanisms underlying intertemporal choice of gains and losses.
Subject(s)
Adult , Female , Humans , Male , Young Adult , Brain , Diagnostic Imaging , Physiology , Brain Mapping , Delay Discounting , Physiology , Magnetic Resonance Imaging , Neural Pathways , Diagnostic Imaging , Physiology , Neuropsychological Tests , Psychophysics , RewardABSTRACT
Neuroimaging has opened new opportunities to study the neural correlates of consciousness, and provided additional information concerning diagnosis, prognosis, and therapeutic interventions in patients with disorders of consciousness. Here, we aim to review neuroimaging studies in chronic disorders of consciousness from the viewpoint of the brain network, focusing on positron emission tomography, functional MRI, functional near-infrared spectroscopy, electrophysiology, and diffusion MRI. To accelerate basic research on disorders of consciousness and provide a panoramic view of unconsciousness, we propose that it is urgent to integrate different techniques at various spatiotemporal scales, and to merge fragmented findings into a uniform "Brainnetome" (Brain-net-ome) research framework.
Subject(s)
Animals , Humans , Brain , Physiology , Chronic Disease , Consciousness , Physiology , Consciousness Disorders , Neuroimaging , Methods , Persistent Vegetative StateABSTRACT
Spinal cord stimulation (SCS) is a promising technique for treating disorders of consciousness (DOCs). However, differences in the spatio-temporal responsiveness of the brain under varied SCS parameters remain unclear. In this pilot study, functional near-infrared spectroscopy was used to measure the hemodynamic responses of 10 DOC patients to different SCS frequencies (5 Hz, 10 Hz, 50 Hz, 70 Hz, and 100 Hz). In the prefrontal cortex, a key area in consciousness circuits, we found significantly increased hemodynamic responses at 70 Hz and 100 Hz, and significantly different hemodynamic responses between 50 Hz and 70 Hz/100 Hz. In addition, the functional connectivity between prefrontal and occipital areas was significantly improved with SCS at 70 Hz. These results demonstrated that SCS modulates the hemodynamic responses and long-range connectivity in a frequency-specific manner (with 70 Hz apparently better), perhaps by improving the cerebral blood volume and information transmission through the reticular formation-thalamus-cortex pathway.
Subject(s)
Adolescent , Adult , Female , Humans , Male , Middle Aged , Young Adult , Brain , Consciousness , Physiology , Consciousness Disorders , Therapeutics , Hemodynamics , Physiology , Pilot Projects , Spinal Cord , General Surgery , Spinal Cord Stimulation , MethodsABSTRACT
Objectives To measure the microstructural differences in the brains of participants with amnestic mild cognitive impairment ( aMCI) and compare with a control group using a magnetic resonance diffusion tensor imaging ( DTI) technique with fully automated image analysis tools. Methods A standardized clinical and neuropsychological evaluation was conducted on each subject 31 participants (15 participants with aMCI, 16 healthy elderly adults) underwent magnetic resonance imaging (MRI)-based DTI. To control the effects of anatomical variation, the diffusion images of all participants were registered to standard anatomical space. Voxel-by-voxel comparisons showed significant regional reductions in white matter regions of fractional anisotropy (FA) in the participants with aMCI as compared with the controls. Results Significantly decreased FA value measurements (P<0. 001) were observed in the right frontal white matter in participants with aMCI. Moreover, there was a statistically significant difference between the patients with aMCI and controls in considering the small regions of bilateral superior frontal gyrus white matter (P < 0.001). Conclusions White matter damage of frontal lobe may play an important role in histopathologic changes associated with amnestic mild cognitive impairment
ABSTRACT
Objective To investigate the executive function of the patients with first-episode schizophrenia,and their relationships with the positive and negative symptoms. And to evaluate the activation characteristics of prefrontal cortex(PFC) in the schizophrenia. Methods Near-infrared spectroscopy(NIRS) was used to assess the activation of the bilateral PFCs during the computerized version of Tower of London(TOL) tasks in schizophrenia and controls. The Positive and Negative Syndrome Scale(PANSS) was used to assess the psychiatric symptoms of the schizophrenia. 40 schizophrenic patients and 40 age- and gender-matched healthy subjects participated in this study. Results ( 1 ) The number of correct TOL responses in patients ( one-move ( 7.35 ± 1. 94 ), two-move ( 7.30 ± 2.53 ), three-move ( 6.58 ± 2.53 ), four-move ( 2.90 ± 1.89 ) ) was significantly less than the healthy controls( one-move (8.82 ± 1.48 ), two-move ( 8.38 ± 1.59 ), three-move ( 7.68 ± 1.47 ), four-move ( 3.73 ±1.71 ); P＜0. 05 ). ( 2 ) There was a significant negative correlation between the patients' task performance and the negative symptom scores(P ＜ 0.05 ). (3) The majority of the prefrontal area was activated in health subjects.Patients were characterized by significant decreased activation in the left PFC during the TOL task compared to healthy subjects. Conclusion Schizophrenic patients have executive function disorder at the initial stage of the disease.The results support that schizophrenia patients have hypofrontality ,and executive function is significantly negatively correlated with negative symptoms. NIRS my be a useful tool for research and clinical assessment for major psychoses.
ABSTRACT
Objective To study the activated status of insula during the performance of word generation task, and to explore the function of different part of insula with functional MRI (fMRI). Methods Twenty-eight subjects were recruited in this study (male 15, female 13), all of them underwent block-designed fMRI with word generation tasks and resting-state scan. SPM 5 and REST 1.3 were used to process the data. Bilateral anterior insula and posterior insula were selected as seeds to calculate the connectivity coefficiency with other voxels, and differences between the anterior and the posterior insula were compared. Results Bilateral anterior insula was significantly activated, while bilateral posterior insula was significantly deactivated. The functional connectivity areas with left anterior insula included right anterior insula, right posterior insula, supplementary motor area (SMA), left superior temporal gyrus, left middle frontal gyrus, left superior frontal gyrus, left inferior parietal lobe, middle cingulate gyrus, right striatum and right inferior frontal gyrus. The functional connectivity areas with left posterior insula included right posterior insula, left anterior insula, right superior temporal gyrus, middle cingulate gyrus, right precentral gyrus and right striatum. The functional connectivity areas with right anterior insula included SMA, left inferior frontal gyrus, right inferior parietal lobe, left inferior parietal lobe, left superior temporal gyrus, right precentral gyrus, right striatum, middle cingulate gyrus, left middle frontal gyrus, left striatum, right middle frontal gyrus, right inferior frontal gyrus and left transverse temporal gyrus. The functional connectivity areas with right posterior insula included right precentral gyrus, left superior temporal gyrus, left anterior insula, left posterior insula, right supramarginal gyrus and middle cingulate gyrus. Conclusion Anterior insula and posterior insula are functionally connected with different areas, and concerned with the language function in different manners. Left lateral anterior insula may play an important role in the language function.